This invention relates to an improvement in a rotary orbital sander of the type wherein the sanding pad has compound rotary and orbital movements.
Tools of the type with which this invention is concerned are disclosed in the patents of T. J. Leveque U.S. Pat. No. 3,205,622, Sept. 14, 1965 and U.S. Pat. No. 3,287,859, Nov. 29, 1966, and the patent of E. B. Heffran, U.S. Pat. No. 3,857,206, Dec. 31, 1974.
The tools of the Leveque patents provide a counterbalance means having a center of gravity which is not in the plane of rotation of the center of gravity of the rotating unbalanced mass of the tool. Accordingly, a complex compound motion is introduced by rotational unbalance causing operator discomfort.
The tool of the Heffran patent has an exposed orbiting carrier member, which can cause harm to the tool operator or damage if contact is made with an object in the vicinity of the work piece.
The tool of the present invention avoids the aforementioned short-comings of the tools of the Leveque and Heffran patents. In addition, the tool of the present invention has features not shown or suggested in either of these two patents, namely, a rolling contact between the rotating sanding pad carrier member and a circular cavity integral with the motor housing which arrangement serves to provide additional rigidity to the tool, and a double antifriction bearing arrangement for the carrier member providing increased rigidity and stability to the tool. Another feature is a shutoff valve operable to disrupt line pressure to the tool so that the tool cannot be inadvertently started and cause harm to personnel or damage to property.
A prime object of this invention is to provide a rotary orbital sander tool having compound rotary and orbital sanding pad movement, which tool has means for balancing the rotary parts to provide smooth, minimal vibration operation.
A further object is to provide a rotary obital sander tool which maximizes the rigidity and stability of the sanding pad carrier.
Still another object is to provide a rotary orbital sanding tool having means to prevent inadvertent starting of the tool.